Take it to someone who knows trannies and ask them to open the side or top and look at the gears and synchros, etc.

Or if it feels good in all the gears probably not much danger in simply putting it to work.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.